In general, a reciprocating compressor is an apparatus for sucking, compressing and discharging gas while a piston reciprocates in a cylinder.
As shown in FIG. 1, a conventional reciprocating compressor includes a casing 110 having a gas suction pipe 112 and a gas discharging pipe 114; a reciprocating motor 130 disposed in the casing 110 for generating a driving force; a compression unit 140 for sucking, compressing and discharging gas by the driving force of the reciprocating motor 130; a resonant spring unit 150 for providing a reciprocating movement of the reciprocating motor with a resonant movement; and a frame unit 120 for supporting the reciprocating motor 130, the compression unit 140 and the resonant spring unit 150 respectively.
The reciprocating motor 130 includes an outer stator 131; an inner stator 132 disposed at a certain air gap between itself and an inner circumference of the outer stator 131; and a magnet paddle 133 formed with a magnet 134 disposed between the outer stator 131 and the inner stator 132, thus to be linearly reciprocated by electromagnetic interaction of the outer and inner stators 131 and 132, and the magnet 134.
The compression unit 140 includes a cylinder 141 having an inner space; a piston 142 disposed in the inner space of the cylinder 141, connected with the magnet paddle 133 of the reciprocating motor 130 to be linearly reciprocated, and, with this reciprocating movement, varying a volume of a compression space (P) in the cylinder 141; a suction valve 143 mounted at a front side of the piston 142 (hereinafter, a side where gas is sucked will be referred to a rear, and a side where compressed gas is discharged to a front), and operated according to pressure in the compression space (P) for opening or closing a suction flow (F) of gas; and a discharging valve 144 installed at a front of the cylinder 141 for opening or closing a discharge of the compressed gas.
The frame unit 120 includes a first frame 121 mounted at a front side of the reciprocating motor 130 and the cylinder 141; a second frame 122 connected with the first frame 121 for supporting the outer stator 131 of the reciprocating motor 130 with the first frame 121; and a third frame 123 connected with the second frame 122 for receiving and supporting the resonant spring unit 150 with the second frame 122.
The resonant spring unit 150 includes a spring seat panel 151 disposed between the second frame 122 and the third frame 123, connected with the piston 142 to be linearly reciprocated; a first spring 152 disposed between the second frame 122 and the spring seat panel 151, and shrunk when the piston 142 moves frontward and elongated when the piston moves rearward; a second spring 153 disposed between the third frame 123 and the spring seat panel 151, and elongated when the piston 142 moves frontward and shrunk when the piston 142 moves rearward.
As shown in FIG. 2, the second frame 122 is formed as a disc shape, and supports the first spring 152. The third frame 123 is formed as a cylindrical shape, and includes a cylindrical portion 123b receiving the first and second springs 152 and 153 and the spring seat panel 151 therein; a spring supporting portion 123c extended from the rear side of the cylindrical portion 123b in an inner circumferential direction thereof, and supporting the second spring 153; and a flange portion 123a extended from a front side of the cylindrical portion 123b in an outer circumferential direction of the cylindrical portion 123b, and fixed at a surface of the second frame 122.
Herein, a spacer 160 is interposed between the second frame 122 and the flange portion 123a of the third frame 123. The spacer 160 is to set an initial location of the piston 142, and, according to a thickness of the spacer 160, a location of the piston 142 in the cylinder 141 is varied.
Operations of the conventional reciprocating compressor configured as above will now be described. When an electric power is applied to the reciprocating motor 130, the magnet paddle 133 is linearly reciprocated by electromagnetic interaction of the outer stator 131, the inner stator 132 and the magnet 134. According to this, the piston 142 connected with the magnet paddle 133 is linearly reciprocated in the cylinder 141, and thus varies a volume of the compression space (P). Accordingly, by change of the volume of the compression space (P), gas is sucked into the compression space (P), compressed, and discharged, and a series of these processes is repeated. At this time, since the first and second springs 152 and 153 supported between the second frame 122 and the third frame 123 provide the reciprocal movement of the piston 142 with a resonant movement, effect of the linear and reciprocal movement of the piston 142 becomes greater.
In the fabrication process of the conventional reciprocating compressor, an additive spacer 160 is inserted between the second frame 122 and the third frame 123 so that an initial location of the piston 142 can be adjusted in consideration of a stroke of the piston 142. According to the thickness of the spacer 160, the location of the piston 142 is adjusted from a dotted line to a solid line of FIG. 2.
However, in the structure for adjusting an initial location of a piston of the conventional reciprocating compressor as above, after determining a thickness of the spacer 160 and assembling the second and third frames 122 and 123, it can be determined whether the initial location of the piston 142 has been properly set or not. So, in case that the thickness of the spacer 160 has been determined inadequately, or a planning location of the piston is changed by production tolerance of the reciprocating compressor, the reciprocating compressor has to be disassembled, and reassembled with repeating the fabrication process.